This invention relates generally to latches and latch assemblies for use in opening and closing vent apparatus. More particularly, this invention relates to an improved over-center type latch assembly, such as those designed particularly for use in sunroof windows or the like in an automotive vehicle, for locking and unlocking a vent panel relative to a stationary main frame.
Over-center type latches are commonly used for locking and unlocking two components mechanically movable relative to each other. For example, over-center type latches are used widely in windows, such as so-called sunroof or moonroof windows in automotive vehicles, wherein a vent panel, typically a pane of glass, is pivotally movable about a hinge along one edge with respect to a stationary frame between a closed position lying substantially within the plane of the frame and an open position supported angularly to the frame to permit air flow through a vent opening. The latch is typically mounted at or near the edge of the vent panel opposite the hinge and includes a pair of mechanical links pivotally connected to each other and respectively pivoted to the frame and to the vent panel. These latch links are designed to pivot through an articulated path of motion moving one link over-center relative to the other for movement between a locked position holding the vent panel closed and an unlocked position permitting swinging movement of the panel to the open position.
One inherent problem encountered with over-center latches of this general type, however, is that relatively large mechanical reaction forces are typically applied to the vent panel and the frame as the latch links are pivoted between the open and closed positions. These mechanical forces act with significant magnitude generally in the plane of the frame and tend to spread the edges of the vent panel and frame adjacent the latch away from one another each time the window is opened or closed. Unfortunately, in a sunroof window for installation into an automotive vehicle, the frame is constructed preferably from a lightweight material, such as aluminum, for minimum weight addition to the vehicle, whereby these mechanical reaction forces can cause deformation of the frame sufficient to prevent proper window operation or to permit leakage of water or the like when the window is closed.
A further disadvantage encountered with many conventional over-center type latches particularly when used with a vehicle sunroof is that the latch links tend to occupy objectionable amounts of passenger headroom within the vehicle both during pivoting movement to the closed position as well as after the window is fully closed. This obstruction of passenger headroom is highly undesirable especially in modern compact vehicles in which headroom is already severely limited. Moreover, the presence of latch structures protruding downwardly into the passenger compartment can present risk of significant head injuries in the event the vehicle is involved in a collision.
There exists, therefore, a significant need for an improved yet relatively simple and easy-to-operate latch assembly designed particularly for use with sunroof windows or the like in automotive vehicles wherein the latch assembly can be operated to open and close the window without applying significant mechanical forces to the window and further wherein the latch assembly provides a relatively low profile at all times to minimize restriction to passenger headroom.